﻿// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information
// 
// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with
// the License. You may obtain a copy of the License at
// 
// http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// 

// .NET Compact Framework 1.0 has no support for reading assembly attributes
#if !NETCF

using System;
using System.Reflection;

using log4net.Repository;

namespace log4net.Config
{
    /// <summary>
    /// Base class for all log4net configuration attributes.
    /// </summary>
    /// <remarks>
    /// This is an abstract class that must be extended by 
    /// specific configurators. This attribute allows the
    /// configurator to be parameterized by an assembly level
    /// attribute.
    /// </remarks>
    /// <author>Nicko Cadell</author>
    /// <author>Gert Driesen</author>
    [AttributeUsage(AttributeTargets.Assembly)]
    public abstract class ConfiguratorAttribute : Attribute, IComparable
    {
        private int m_priority = 0;

        /// <summary>
        /// Constructor used by subclasses.
        /// </summary>
        /// <param name="priority">the ordering priority for this configurator</param>
        /// <remarks>
        /// <para>
        /// The <paramref name="priority"/> is used to order the configurator
        /// attributes before they are invoked. Higher priority configurators are executed
        /// before lower priority ones.
        /// </para>
        /// </remarks>
        protected ConfiguratorAttribute(int priority)
        {
            this.m_priority = priority;
        }

        /// <summary>
        /// Configures the <see cref="ILoggerRepository"/> for the specified assembly.
        /// </summary>
        /// <param name="sourceAssembly">The assembly that this attribute was defined on.</param>
        /// <param name="targetRepository">The repository to configure.</param>
        /// <remarks>
        /// <para>
        /// Abstract method implemented by a subclass. When this method is called
        /// the subclass should configure the <paramref name="targetRepository"/>.
        /// </para>
        /// </remarks>
        public abstract void Configure(Assembly sourceAssembly, ILoggerRepository targetRepository);

        /// <summary>
        /// Compare this instance to another ConfiguratorAttribute
        /// </summary>
        /// <param name="obj">the object to compare to</param>
        /// <returns>see <see cref="IComparable.CompareTo"/></returns>
        /// <remarks>
        /// <para>
        /// Compares the priorities of the two <see cref="ConfiguratorAttribute"/> instances.
        /// Sorts by priority in descending order. Objects with the same priority are
        /// randomly ordered.
        /// </para>
        /// </remarks>
        public int CompareTo(object obj)
        {
            // Reference equals
            if ((object)this == obj)
            {
                return 0;
            }

            int result = -1;

            ConfiguratorAttribute target = obj as ConfiguratorAttribute;
            if (target != null)
            {
                // Compare the priorities
                result = target.m_priority.CompareTo(this.m_priority);
                if (result == 0)
                {
                    // Same priority, so have to provide some ordering
                    result = -1;
                }
            }
            return result;
        }
    }
}

#endif //!NETCF
